JP2003229614A - Magnetic material, magnetoresistance effect device using such magnetic material and magnetic device using such magneto resistive effect device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic material using a new half metal, to provide a magnetoresistance effect device in which a high tunnel magneto resistance effect can be obtained by producing the magnetoresistance effect device by using such a magnetic material, and further to provide a magnetic device using such a magneto resistance effect device. <P>SOLUTION: The magnetoresistance effect device is provided with a fixed layer 3 composed of a ferromagnetic substance, an insulating layer 4 formed on that fixed layer, and a free layer 5 formed on that insulating layer and composed of a ferromagnetic substance. Any one of or both the fixed layer 3 and the free layer 5 are each composed of a metal oxide having a spinel structure expressed by M<SB>x</SB>Fe<SB>3-x</SB>O<SB>4</SB>and (x) fulfills the condition of 0<x<0.5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic material made of a metal oxide having a spinel structure, a magnetoresistive effect element using the magnetic material, and a magnetic device using the magnetoresistive effect element.

[0002]

2. Description of the Related Art The magnetoresistive effect is a phenomenon in which the electric resistance of a ferromagnetic material changes when a magnetic field is applied to the ferromagnetic material. Magnetic sensors, magnetic heads, and the like can be cited as examples that utilize this magnetoresistive effect. Conventionally, as a magnetic material used for these, there has been a Fe-Ni alloy permalloy thin film. The magnetic resistance change rate of this permalloy thin film was as low as about 2 to 3%, and sufficient sensitivity was not obtained.

On the other hand, in recent years, GMR (Giant Magnetoresistance) has attracted attention as a magnetoresistive effect element exhibiting a very large magnetoresistive effect based on a new mechanism. GMR is an artificial lattice in which magnetic layers and non-magnetic layers are alternately laminated at a period of about several nm, and magnetic moments of magnetic layers at opposite positions are magnetically coupled in an antiparallel state. It is a film. As this GMR, for example, an artificial lattice film of Fe / Cr (MNBaibich et al., Physic
al Review Letters, Vol.61, No.21, pp.2472-2475, Th
e American Physical Society, 1988), Co
/ Cu artificial lattice film (SSPParkin et al., Physical
Review Letters, Vol.66, No.16, pp.2152-2155, The A
The American Physical Society, published in 1991) has been found.

As a GMR capable of switching spins with a small magnetic field, a spin valve film in which ferromagnetic layers are laminated with a nonmagnetic metal layer is known. In this GMR, the thickness of the nonmagnetic metal layer is increased to the extent that exchange coupling between the ferromagnetic layers is eliminated, and an antiferromagnetic film such as FeMn or IrMn is arranged so as to be in contact with one of the ferromagnetic layers. Exchange coupled. As a result, the magnetic moment of the ferromagnetic layer (fixed layer) in contact with the antiferromagnetic film is fixed, and the spin of the other ferromagnetic layer (free layer) can be easily switched by the external magnetic field. By using this spin valve film as a magnetoresistive effect element, it becomes possible to construct a magnetoresistive effect element having higher sensitivity than the artificial lattice film described above.

The magnetoresistive effect element described above obtains a magnetoresistive effect when a current is passed in a direction parallel to the film surface, while a current is passed in a direction perpendicular to the film surface. A magnetoresistive element that produces a magnetoresistive effect when flowing is also known (WPPratt et al., Phys
ical Review Letters, Vol.66, No.23, pp.3060-3063, T
he American Physical Society, 1991).

A high magnetoresistive effect can be obtained by providing a thin insulating layer between two ferromagnetic layers.
R (Tunnel Magenetoresistance) has been found (T. Miyazaki et al. Journal of Magnetism and Magne
tic Materials 139, pp. 231-234, Elsevier Science
BV, issued in 1995). The magnetoresistive effect in this TMR utilizes the fact that the magnitude of the tunnel current in the direction perpendicular to the film surface varies depending on the spin direction of the free layer, and is particularly called the tunnel magnetoresistive effect.

Furthermore, a ferromagnetic double tunnel magnetoresistive element (K. K., comprising five layers of ferromagnetic material layer / insulating layer / ferromagnetic material layer / insulating layer / ferromagnetic material layer having two insulating layers). Inomata
et al., Journal of Applied Physics, Vol.87, No 9,
pp.6064-6066, American Institute of Physics, 2000
Issue), and a ferromagnetic double tunnel magnetoresistive effect element (K. Inom) having a granular structure in which the central ferromagnetic material is made into fine particles in this ferromagnetic double tunnel magnetic effect element.
ata et al., Journal of Applied Physics, Vol.73, No
8, pp.1143-1145, American Institute of Physics, 2
000 years) has been proposed by the present inventors.

Magnetoresistance change rate MR in the above-mentioned TMR
Generally depends on the spin polarization P of the ferromagnetic material and is theoretically given by the following equation.

MR = 2P ₁ P ₂ / (1-P ₁ P ₂ ) ... (1) where P ₁ is the spin polarization of the first ferromagnetic material, and P ₂ is It is the spin polarization of the second ferromagnet. The spin polarization is a degree of deviation between up-spin and down-spin of electrons in the outermost shell that contribute to electric conduction, and 0 ≦
It takes a value of P ≦ 1. The maximum rate of change in magnetoresistance at room temperature obtained at present is 0.
It is about 5.

Since the TMR is excellent in temperature stability and has a wide operating temperature range, it has already been applied to a magnetic head and a magnetic sensor, and recently, a magnetic recording element (magnetoresistive effect memory, MRAM (Magnetic Random Access). Mem
ory) etc.) is being applied to.

For example, in the MRAM, TMRs are arranged in a matrix, and a magnetic field is applied to the TMRs by passing a current through a wiring provided in the vicinity of the TMRs, so that the magnetization directions of the free layer are parallel / antiparallel. By controlling
Data is written in TMR. Further, at the time of reading, data is detected by flowing a current in the direction perpendicular to the film surface of the TMR by using the tunnel magnetoresistive effect described above. However, in the MRAM, if the element size is reduced for higher density, noise due to element variation increases,
There is a problem that the current magnetoresistance change rate is insufficient.
Therefore, it is necessary to develop a TMR that exhibits a larger magnetoresistance change rate.

As can be seen from the equation (1), an infinitely large TMR is expected when a magnetic material with P = 1 is used. P = 1
The magnetic material of is generally called half metal, and so far,
_{NiMnSb, Fe 8 O 4, CrO} 2, (La-Sr) M
Various half metals such as nO ₄ , Th ₂ MnO ₇ and Sr ₂ FeMoO ₆ have been developed. However, although an attempt was made to produce TMR using these half metals,
In both cases, the magnetoresistance change rate at room temperature was small, contrary to expectations,
It remains around 10%. The magnetoresistance change rate (MR ratio) of the actually manufactured magnetoresistive effect element is calculated here with R _{1 as} the tunnel resistance when the magnetization direction of the free layer is parallel to the magnetization direction of the fixed layer. , MR ratio (%) = 100 × (R ₂ −R ₁ ) / R ₁ (2) where R ₂ is the tunnel resistance when antiparallel.

Most recently, in a granular structure in which Zn _0.41 Fe _2.59 O ₄ crystal grains are dispersed in an insulating α-Fe ₂ O ₃ matrix, a large T of 158% at room temperature is obtained.
MR was observed (P. Chen et al., Physical Review L
etters, Vol.87, No.10, 107202, The American Physic
al Society, published 2001). This material is ZnO and Fe
_{(NO 3) 3 · 9H 2} O and the powder obtained by pulverizing after calcination at 1100 ° C. The mixture powder was prepared by sol-gel method using a compression molded into a disk shape, and sintered at 1400 ° C. It is a bulk material. However, because of the granular structure, the orientation of the crystal grains is irregular, and therefore the magnetic field in which 158% TMR develops is 5 kOe (≈3.9).
3 × 10 ⁶ A / m) or more, which is extremely large. Therefore, there seems to be a problem in terms of practicality.

[0014]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic material using a new half metal, and to manufacture a magnetoresistive effect element using this, to obtain a high tunnel magnetoresistive effect. Another object of the present invention is to provide a magnetoresistive effect element, and further to provide a magnetic device using this magnetoresistive effect element.

[0015]

The magnetic material according to the present invention is a magnetic material containing a metal oxide, and the metal oxide has a spinel structure represented by the general formula M _x Fe _3-x O _4. , M is either Zn or Mn, and x is 0
<X <0.5 is satisfied.

The present inventors have focused their attention on half metal and have conducted earnest research in order to develop a magnetic material with a higher magnetoresistive effect. As a result, a metal oxide having a spinel structure represented by M _x Fe _3-x O ₄ , M is either Zn or Mn, and x is 0 <x <
The inventors have found that a magnetic material satisfying 0.5 can provide a high magnetoresistive effect, and have completed the present invention. The most significant feature of the present invention is that the above composition provides a high magnetoresistive effect in a small magnetic field at room temperature and has a practical resistance value when applied to various magnetic devices and the like. No known magnetic material has a high magnetoresistive effect and its resistance value is within a practical range.

A magnetoresistive effect element according to the present invention comprises:
A ferromagnetic layer, an insulating layer formed on the first ferromagnetic layer, and a second ferromagnetic layer formed on the insulating layer. At least one of the first ferromagnetic layer and the second ferromagnetic layer has a general formula M _x
It contains a metal oxide having a spinel structure represented by Fe _3-x O ₄ , M is either Zn or Mn, and x satisfies 0 <x <0.5.

As described above, a tunnel magnetoresistive effect element having a high magnetoresistive effect is provided by manufacturing a ferromagnetic tunnel junction of a ferromagnetic layer / insulating layer / ferromagnetic layer using the above magnetic material. It becomes possible to do.

The magnetoresistive effect element according to the present invention is a magnetoresistive effect element having a granular structure in which granular magnetic materials are dispersed in an insulating layer, and the magnetic material is represented by the general formula M _x Fe _3-x. It contains a metal oxide having a spinel structure represented by O ₄ , M is either Zn or Mn, and x satisfies 0 <x <0.5.

As described above, even in the magnetoresistive effect element having the granular structure in which the granular magnetic material is dispersed in the insulating layer, it is possible to obtain a high magnetic resistance by using the granular magnetic material as the magnetic material satisfying the above condition. The magnetoresistive effect can be obtained.

A magnetic device according to the present invention is constructed using any of the magnetoresistive effect elements described above.

As described above, by manufacturing a magnetic device using any of the magnetoresistive effect elements described above, it becomes possible to provide a high-performance magnetic device. As the magnetic device, a magnetic head, a magnetic sensor,
Magnetoresistive memory, MRAM, etc. are considered.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Spinel ferrite, which is a type of metal oxide having a spinel structure, is generally represented by the chemical formula MFe ₂ O ₄ , and its unit cell has a three-dimensional structure in which parts I and II shown in FIG. It has an alternating structure. Here, M is Zn, Mn, Fe, Co, Ni, C
Fe is a divalent ion such as u, Mg and Li, and Fe is a trivalent iron ion. The unit cell of spinel ferrite is composed of 8 ions represented by the molecular formula MFe ₂ O ₄ , and there are two sites, A site and B site, in which the metal ions enter crystallographically different.

Throughout Part I and Part II, O ²⁻ ions exhibit face centered cubic packing. In the part I, Fe ions are located in the space of octahedral 6-coordination of O (B site), and in the part II, in the space of tetrahedral tetracoordination of O (A site) M.
Ion is located. There are a positive spinel and an inverse spinel depending on how the metal ions enter. The one in which the divalent ion M enters the A site is called the positive spinel, and the one in the B site is the reverse spinel. Therefore, the positive spinel ferrite is (M ²⁺ ) [Fe ³⁺ ₂ ] O ₄ and the reverse spinel ferrite (Fe
³⁺ ) [Fe ³⁺ M ²⁺ ] O ₄ . Here, () represents the A site, and [] represents the B site. It is known that the positive spinel ferrite is only the case where M is Zn, Cd, and Mn, and the other is the reverse spinel ferrite.

In spinel ferrite, the negative exchange interaction between A site and B site (between A and B) is the largest,
It is a small negative value between A and A and between B and B.
Therefore, in the inverse spinel ferrite, the magnetization value is determined only by the magnitude of the spin of Mn ²⁺ . On the other hand, in the case of positive spinel phyllite, the exchange interaction between A and B is 0 when M is a non-magnetic element, and the negative spin interaction between B and B makes it an antiferromagnetic material. Therefore, Zn ferrite and Cd ferrite are antiferromagnetic materials.

When the amount of M in the positive spinel phyllite is smaller than 1, the position where M is insufficient is Fe ^3+.
Occupies, and becomes (M _x Fe _1-x ) [Fe ₂ ] O ₄ . As a result, even if M is a non-magnetic element, (1 + x) Fe
Magnetization corresponding to ³⁺ occurs and becomes a ferromagnetic material.

In general, many oxide magnetic materials have a large Hund's bond and exhibit a half metal. Magnetite (Fe ₃ O ₄ ) which is a kind of spinel ferrite is also a half metal, and a tunnel magnetoresistive effect element using the same is manufactured. However, since Fe ₂ O ₃ is more stable as an oxide of Fe, it is very difficult to manufacture magnetite, and this seems to be the reason why a large magnetoresistance change rate is not obtained.

The magnetic material of the present invention has a positive spinel ferrite M _x Fe in which M is Zn, Mn or a mixture thereof.
It is based on the finding that a large TMR is obtained at room temperature by using _3-x O ₄ (0 <x <0.5). It should be noted that when x = 0, it is difficult to manufacture because of the composition representing magnetite, and when x ≧ 0.5, the Curie point becomes lower than room temperature, so that a large magnetoresistance change rate cannot be obtained at room temperature. Further, M is limited to Zn, Mn, and a mixture thereof because other materials have too high a resistance and are not practical for use as a magnetoresistive effect element.

As the tunnel magnetoresistive effect element using the above-mentioned magnetic material, it is conceivable that it is formed by laminating multiple layers on the surface of the semiconductor substrate 1 as shown in FIG. Specifically, the TMR 10 composed of the ferromagnetic layer 3 / insulating layer 4 / ferromagnetic layer 5 is a multilayer further sandwiched by the conductor layer 2 which is the lower electrode layer and the conductor layer 6 which is the upper electrode layer. It has a laminated structure. When used as a spin valve film, for example, the semiconductor substrate 1
FeMn between the ferromagnetic layer 3 and the conductor layer 2 located on the side
An antiferromagnetic layer such as IrMn is provided, and the magnetization direction of the ferromagnetic layer 3 is fixed by exchange coupling.

As another magnetoresistive effect element, a magnetoresistive effect element having a granular structure as shown in FIG. 3 can be considered. Conductor layer 2 is formed on the surface of semiconductor substrate 1.
And an insulating layer 7 including a granular ferromagnetic layer 8 made of the magnetic material of the present invention is further laminated thereon. Further, by laminating the conductor layer 6 thereon, a magnetoresistive effect element is formed. Furthermore, multiple tunnel junctions are also conceivable, and the magnetoresistive effect element of the present invention may be in any form as long as it is a tunneling magnetoresistive effect element using the magnetic material having the above composition.

In the case of application to a magnetoresistive effect element, at least one layer may contain the magnetic material having the above composition. Furthermore, as an insulator which brings about the tunnel effect, a non-magnetic insulator having a spinel structure such as ZnAl ₂ O ₄ or MgAl ₂ O ₄ , an oxide such as Al ₂ O ₃ or A
Various insulators such as a nitride such as 1N and a fluoride such as CaF ₂ can be used. When manufacturing a tunnel magnetoresistive effect element, a sputtering method, a vapor deposition method, a laser ablation method, an MBE (Molecular Beam) method, etc.
It can be manufactured using a normal thin film manufacturing method such as the Epitaxy method.

(Examples) Examples of the present invention will be described below.

Example 1 As shown in FIG. 4A, in this example, a tunnel magnetoresistive effect element containing a magnetic material according to the present invention was manufactured. Specifically, MgO (10
0) Cr (5 nm) / Zn _0.35 F on the substrate by laser ablation method using targets of each constituent material
e _2.65 O ₄ (10 nm) / ZnAl ₂ O ₄ (2 nm) / Z
was manufactured multilayer laminated film of the _{n 0.35 Fe 2.6 5 O 4 (} 20nm) / Cr (5nm). Here, the Cr layer is a conductor layer serving as the lower and upper electrodes, and the ZnAl ₂ O ₄ layer is a tunnel insulating layer. 100 Oe (≈7.85 × 10 ⁴ A /
The magnetic field of m) was applied to introduce uniaxial anisotropy in the film plane. A cross-sectional TEM (Transmission
Electron Microscope) confirmed that each element film was epitaxially grown.

This laminated film was microfabricated using photolithography to fabricate a micro tunnel magnetoresistive effect element of 4 μm × 4 μm. As a result of measuring the magnetic resistance using the so-called four-terminal method, a magnetoresistive effect curve (see FIG. 4B) due to the coercive force difference between the upper and lower Zn _0.35 Fe _2.65 O ₄ films was obtained, and 30 Oe (≈2. With a small magnetic field of 36 × 10 ⁴ A / m), the MR ratio at room temperature was a very large value of about 180%. This means that the Zn _0.35 Fe _2.65 O ₄ film has a very high spin polarization rate and suggests that it is a half metal. In the measurement result of FIG. 4B, the forward path in which the magnitude and direction of the magnetic field were sequentially changed from −50 Oe to +50 Oe and +50 Oe.
And the return path changed from −50 Oe to −50 Oe.

Example 2 As shown in FIG. 5A, in this example, a tunnel magnetoresistive effect element containing a magnetic material according to the present invention was manufactured. Specifically, MgO (10
0) Cr (5 nm) / Zn on the substrate by MBE method
_0.35 Fe _2.65 O ₄ (10 nm) / ZnAl ₂ O ₄ (2n
m) / Zn _0.35 Fe _2.65 O ₄ (20 nm) / Cr (5n
The multilayer laminated film of m) was produced. The Cr layer is a conductor layer serving as lower and upper electrodes, and the ZnAl ₂ O ₄ layer is a tunnel insulating layer. 100 Oe (≈7.85 × 10 ⁴ A /
The magnetic field of m) was applied to introduce uniaxial anisotropy in the film plane. When the sample obtained as a result was observed by a cross-sectional TEM, it was confirmed that each element film was epitaxially grown.

This laminated film was microfabricated using photolithography to fabricate a micro tunnel magnetoresistive effect element of 4 μm × 4 μm. As a result of measuring the magnetic resistance using the so-called four-terminal method, a magnetoresistive effect curve (see FIG. 5B) due to the difference in coercive force between the upper and lower Zn _0.35 Fe _2.65 O ₄ films was obtained, and 30 Oe (≈2. With a small magnetic field of 36 × 10 ⁴ A / m), the MR ratio at room temperature was a very large value of about 140%. This means that the Zn _0.35 Fe _2.65 O ₄ film has a very high spin polarization rate and suggests that it is a half metal.

(Embodiment 3) As shown in FIG. 6A, C was formed on a thermally oxidized Si substrate by magnetron sputtering.
r (5 nm) / Zn _0.2 Fe _2.8 O ₄ (10 nm) / Al
O _x (2 nm) / CoFe (5 nm) / IrMn (5n
m) / Cr (5 nm) multilayer laminated film was produced. AlO
_{The x} film is a tunnel insulating layer and was produced by plasma-oxidizing Al.

This laminated film was microfabricated using photolithography to fabricate a micro tunnel magnetoresistive effect element of 4 μm × 4 μm. As a result of measuring the magnetoresistance using the so-called 4-terminal method, the magnetoresistance effect curve shown in FIG. 6 (b) is obtained, and the MR at room temperature in a small magnetic field of 50 Oe (≈3.93 × 10 ⁴ A / m) It showed a very large value of about 75%. This means that the Zn _0.2 Fe _2.8 O ₄ film has a very high spin polarization rate and suggests that it is a half metal.

As described above, according to the present invention, since a magnetoresistive effect element having a very large tunnel magnetoresistive effect can be obtained, it can be considered to be applied to various magnetic devices. Hereinafter, the application example will be illustrated.

(Application Example 1) FIG. 7 is a diagram showing a case where the magnetoresistive effect element of the present invention is applied to a magnetic head. The magnetic head is composed of a reproducing head including the TMR 10 on a base 22, and a recording head 26 including a magnetic pole 23, a coil 21, and an upper magnetic pole 24. The magnetic head writes or reads signals on the recording medium.

FIG. 8 is a sectional view for explaining the structure of this reproducing head. Referring to the figure, TMR 10 including ferromagnetic layer 3, insulating layer 4 and ferromagnetic layer 5 has a structure sandwiched between upper and lower electrode layers 32 and 34, and shield 31 and 35 is located.
Further, in order to maintain the magnetic stability of the ferromagnetic layer 5 whose magnetization direction changes according to the change of the external magnetic field, a permanent magnet 33 is arranged in the vicinity of the TMR 10, and these are connected to the TMR 10 via an insulating film. Has been done.

(Application Example 2) FIG. 9 is a circuit diagram showing a case where the magnetoresistive effect element of the present invention is applied to a magnetic sensor. In the magnetic sensor, four TMRs 10 form a Wheatstone bridge circuit, and two of them have a magnetic shield 41. By using TMR as in the present magnetic sensor, not only the sensitivity can be improved by obtaining a high magnetoresistance change rate, but also the resistance can be increased because the insulating layer is sandwiched between two magnetic layers. It will be easier. In addition, a sufficiently high resistance can be obtained even with a micrometer-sized element, which enables high-density mounting by photolithography and is advantageous in terms of power consumption.

(Application Example 3) FIG. 10 is a circuit diagram showing an example in which the magnetoresistive effect element of the present invention is applied to a magnetic memory device. The memory cells formed of a laminated body of the diode 53 and the TMR 10 are arranged in a matrix.
The stacked body of the diode 53 and the TMR 10 is formed on the bit line (BL) 51, and one end of the diode 53 and the bit line 51 are connected. A word line (WL) 52 arranged orthogonal to the bit line 51 is connected to the other end of the TMR 10.

Application Example 4 FIGS. 11 and 12 are a circuit configuration diagram and a sectional view of a memory cell portion showing an example in which the magnetoresistive effect element of the present invention is applied to an MRAM.
As shown in FIG. 12, the gate electrode 6 is formed on the silicon substrate 60.
3, the transistor 64 including the source / drain regions 65 and 66 is formed. The gate electrode 63 constitutes a read word line (WL). A digit line (DL) 62 for writing is formed on the gate electrode 63 via an interlayer insulating layer. A contact metal 67 is connected to the drain region 66 of the transistor 64, and a base layer 68 is connected to the contact metal 67. The TM of the present invention is provided at a position above the write digit line 62 on the base layer 68.
R10 is formed. A bit line 61 is connected to the TMR 10.

As shown in FIG. 11, the memory cells including the transistors 64 and the TMR 10 are arranged in a matrix. The read word line 63, which also serves as the gate electrode of the transistor 64, and the write digit line 62 are arranged in parallel. Also, TMR
The bit line 61 connected to the other end (upper part) of 10 is
It is arranged orthogonally to the word line 63 and the digit line 62.

As described above, the MR is significantly higher than the conventional one.
A high-performance magnetic device is provided by constructing a magnetoresistive effect element using the magnetic material of the present invention capable of obtaining a ratio, and further manufacturing various magnetic devices as described above using this magnetoresistive effect element. It becomes possible to do.

The above-described embodiment disclosed this time is an example in all respects, and is not restrictive. The technical scope of the present invention is defined by the claims, and includes the meaning equivalent to the description of the claims and all modifications within the scope.

[0049]

According to the present invention, a magnetic material exhibiting a very large tunnel magnetoresistive effect at room temperature can be obtained. By forming a magnetoresistive effect element using this magnetic material, a magnetoresistive material having an extremely high MR ratio can be obtained. It becomes possible to provide an effect element. Furthermore, by applying this magnetoresistive effect element to various magnetic devices, high-performance magnetic devices can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the structure of spinel ferrite.

FIG. 2 is a cross-sectional view for explaining the structure of the magnetoresistive effect element according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining the structure of the magnetoresistive effect element having the granular structure in the embodiment of the present invention.

FIG. 4A is a sectional view for explaining the structure of the magnetoresistive effect element in Example 1 of the present invention,
(B) is a figure showing a result of measuring a magnetoresistive effect of this magnetoresistive effect element.

FIG. 5A is a cross-sectional view for explaining the structure of the magnetoresistive effect element according to the second embodiment of the present invention,
(B) is a figure showing a result of measuring a magnetoresistive effect of this magnetoresistive effect element.

FIG. 6A is a sectional view for explaining the structure of a magnetoresistive effect element according to Example 3 of the present invention,
(B) is a figure showing a result of measuring a magnetoresistive effect of this magnetoresistive effect element.

FIG. 7 is a diagram for explaining a case where the magnetoresistive effect element of the present invention is applied to a magnetic head.

8 is a cross-sectional view of the reproducing head portion shown in FIG.

FIG. 9 is a circuit configuration diagram of a magnetic sensor for explaining a case where the magnetoresistive effect element of the present invention is applied to a magnetic sensor.

FIG. 10 is a circuit configuration diagram of a magnetic memory when the magnetoresistive effect element of the present invention is applied to the magnetic memory.

FIG. 11 is a circuit configuration diagram of an MRAM when the magnetoresistive effect element of the present invention is applied to the MRAM.

FIG. 12 is a sectional view of a memory cell portion of an MRAM when the magnetoresistive effect element of the present invention is applied to the MRAM.

[Explanation of symbols]

1 substrate, 2 conductive layer, 3 ferromagnetic layer (fixed layer),
4 insulating layers, 5 ferromagnetic layers (free layers), 6 conductive layers, 7 insulating layers, 8 granular ferromagnetic layers, 9 antiferromagnetic layers, 10 TMR, 21 coils, 22 bases, 23
Magnetic pole, 24 upper magnetic pole, 26 recording head, 31, 35 shield, 32, 34 electrode layer, 33 permanent magnet, 41 shield, 51 bit line, 52 word line, 5
3 diode, 60 substrate, 61 bit line, 62
Digit line, 63 word line (gate electrode),
64 transistor, 65, 66 source / drain region, 67 contact metal, 68 base layer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 10/32 H01L 27/10 447 H01L 27/105 G01R 33/06 R (72) Inventor Takashi Naganaga Tokyo 2-3 2-3 Marunouchi, Chiyoda-ku, Sanryo Electric Co., Ltd. (72) Inventor Yutaka Takada Tokyo 2-3, Marunouchi, Chiyoda-ku Sanryo Electric Co., Ltd. (72) Inventor Koichiro Inomata Sendai, Miyagi Prefecture 12 F term at 1-7 Kurio, Aoba-ku, Aichi (reference) 2G017 AA10 AD55 5D034 BA02 5E049 AB04 BA12 BA16 5F083 FZ10 LA12 LA16

Claims (4)

[Claims] 1. A magnetic material containing a metal oxide, wherein the metal oxide has a spinel structure represented by the general formula M _x Fe _3-x O ₄ , and M is either Zn or Mn. Yes, and x is 0 <x
A magnetic material satisfying <0.5. 2. A first ferromagnetic material layer, an insulating layer formed on the first ferromagnetic material layer, and a second ferromagnetic material layer formed on the insulating layer. A magnetoresistive effect element including, wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer has a spinel structure represented by the general formula M _x Fe _3-x O _4. Contains metal oxide, M is Zn
Or Mn, and x is 0 <x <0.5.
A magnetoresistive effect element that satisfies the requirements. 3. A magnetoresistive effect element having a granular structure in which granular magnetic materials are scattered in an insulating layer, wherein the magnetic material has a spinel structure represented by the general formula M _x Fe _3-x O _4. A magnetoresistive effect element containing a metal oxide having, M being either Zn or Mn, and x satisfying 0 <x <0.5. 4. A magnetic device comprising the magnetoresistive effect element according to claim 2.